Conventionally, a coffee pot for making coffee and an oriental herb medicine pot for extracting herb extract have electric heating means built in the bottom. On the other hand, most of boiling pots employ as their heat source external heat source such as a gas range.
But, as in a process of cook by the gas range by using conventional pot, when food having a lot of water or broth in them reaches the boiling point, the water or broth often overflows with steam while lifting a lid. If left alone, the flame of the gas range is putted out by the overflowing water and broth, and in worse case, have to supply water and newly add the flavoring according to the additional water in the case of food.
On the other side, in order to the prevent the overflowing it is often left open, without the lid on, even while cooking, or the lid has to be opened now and then, and sometimes the strength of the fire for cook pot has to be correctly adjusted.
But, cooking without a lid, that has disadvantage in the thermal efficiency side, lifting a lid often while cooking troublesome and will cause loss of heat, so more cooking time is required and difficulty in a rational control of the state of cooking.
On the other hand, it is quite troublesome to control the strength of fire directly and difficult to adjust time and extent in correctly.